Set up user access for Anthos Identity Service

This document is for cluster administrators who have already configured clusters for Anthos Identity Service following the instructions in Configure clusters for fleet-level Anthos Identity Service or Configure clusters for Anthos Identity Service with OIDC. It tells you how to set up (and restrict) access to your configured cluster for your organization's developers and other cluster users.

Set up user login access

After you have configured a cluster, you need to generate a login configuration file and distribute it to cluster users. This file lets users log in to the cluster from the command line with your chosen provider, as described in Access clusters with Anthos Identity Service.

With OIDC providers only, users can also log in to the cluster from the Google Cloud console without a login file, as described in Work with clusters from the Google Cloud console.

Generate the login config

Console

(Fleet-level setup only)

Copy the displayed gcloud command and run it to generate the file.

gcloud

If you configured the cluster using the CLI, or if you need to generate the file again, run the following create-login-config command to generate the file:

gcloud anthos create-login-config --kubeconfig=KUBECONFIG

...where KUBECONFIG is the path to the kubeconfig file for the cluster. If there are multiple contexts in the kubeconfig, the current context is used. You may need to reset the current context to the correct cluster before running the command.

You can see complete reference details for this command, including additional optional parameters, in the Google Cloud CLI reference guide.

The default name for the login config file is kubectl-anthos-config.yaml, which is the name the Google Cloud CLI expects when using the file to log in. If you want to change this to a non-default name, see the relevant section in Distribute the login config below.

For troubleshooting information related to user access, see Troubleshoot user access issues.

Distribute the login config

The following are some possible approaches to distributing the config file:

• Host the file at an accessible URL. Users can specify this location with the --login-config flag when running gcloud anthos auth login, allowing the Google Cloud CLI to get the file.

  Consider hosting the file on a secure host. See the --login-config-cert flag of the gcloud CLI for more information about using PEM certificates for secure HTTPS access.

• Manually provide the file to each user, with information on where to save it on their local machine—the Google Cloud CLI expects to find the file in an OS-specific default location. If the file has a non-default name or location, your users must use the --login-config flag to specify the config file location when running commands against the cluster. Instructions for users to save the file are in Access clusters with Anthos Identity Service.

• Use your internal tools to push the authentication configuration file onto each user's machine. The Google Cloud CLI expects to find the file in the following locations, depending on the user OS:

  Linux

  $HOME/.config/google/anthos/kubectl-anthos-config.yaml

  macOS

  $HOME/Library/Preferences/google/anthos/kubectl-anthos-config.yaml

  Windows

  %APPDATA%\google\anthos\kubectl-anthos-config.yaml

Set up role-based access control (RBAC)

Authentication is often combined with Kubernetes role-based access control (RBAC) to provide more finely grained access control to clusters for authenticated users and service accounts. Whenever possible, it is recommended to create RBAC policies that use group names instead of user identifiers. By linking your RBAC policies explicitly to groups, you can manage user access privileges entirely with your identity provider, so the cluster doesn't need to be updated every time user privileges change. Note that to configure access control based on membership of security groups with OIDC, you must ensure that Anthos Identity Service is set up to support getting group membership information from your identity provider.

For example, if you wanted certain authenticated users to have access to the cluster's Pods, create a ClusterRole that grants access to these resources, as in the following example:

apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  name: pod-reader
rules:
- apiGroups: [""]
  # The resource type for which access is granted
  resources: ["pods"]
  # The permissions granted by the ClusterRole
  verbs: ["get", "watch", "list"]

You then create a corresponding ClusterRoleBinding to grant the permissions in the ClusterRole to the relevant users—in this case, members of the us-east1-cluster-admins security group and the user with ID u98523-4509823:

apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  name: read-pods-admins
subjects:
  # Grants anyone in the "us-east1-cluster-admins" group
  # read access to Pods in any namespace within this cluster.
- kind: Group
  name: gid-us-east1-cluster-admins # Name is case-sensitive
  apiGroup: rbac.authorization.k8s.io
  # Grants this specific user read access to Pods in any
  # namespace within this cluster
- kind: User
  name: uid-u98523-4509823
  apiGroup: rbac.authorization.k8s.io
roleRef:
  kind: ClusterRole
  name: pod-reader
  apiGroup: rbac.authorization.k8s.io

Note: If your identity provider returns a group name that contains double backslash characters, then one of the backslash characters should be omitted when you reference the group name in the ClusterRoleBinding resource. For example, if you have created a group named corp\\my-group, reference it in the ClusterRoleBinding resource as corp\my-group. This is because the first backslash character is treated as an escape character.

You can find out much more about using RBAC in Configure role-based access control and Using RBAC Authorization.

Create an RBAC role for Google Cloud console access

Users authenticated using OIDC providers can log in to clusters from the Google Cloud console as well as the command line.

Authenticated users who want to access a cluster's resources in the Google Cloud console need to have the relevant Kubernetes permissions to do so. If you don't want to grant those users more extensive permissions, such as those of a cluster admin, you can create a custom RBAC role that includes the minimum permissions to view the cluster's nodes, persistent volumes, pods, and storage classes. You can define this set of permissions by creating a ClusterRole RBAC resource, cloud-console-reader, in the cluster.

cloud-console-reader grants its users the get, list, and watch permissions on the cluster's nodes, persistent volumes, pods and storage classes, which allow them to see details about these resources.

kubectl

To create the cloud-console-reader ClusterRole and apply it to the cluster, run the following command:

cat <<EOF > cloud-console-reader.yaml
kind: ClusterRole
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: cloud-console-reader
rules:
- apiGroups: [""]
  resources: ["nodes", "persistentvolumes", "pods"]
  verbs: ["get", "list", "watch"]
- apiGroups: ["storage.k8s.io"]
  resources: ["storageclasses"]
  verbs: ["get", "list", "watch"]
EOF
kubectl apply -f cloud-console-reader.yaml

You can then grant this ClusterRole to users when setting up your permission policies, as described in the previous section. Note that users also need IAM permissions to view clusters in the Google Cloud console.